Flexible display panel, due to its characteristics of light weight, bendability, impact resistance and shatter resistance, becomes one of the development trends of future display technology. At present, glass substrates are generally used as carriers in manufacturing flexible display panels. First, a plastic substrate is formed on a glass substrate. Specifically, plastic raw material such as polyimide may be coated on the glass substrate and then dried and solidified to form the plastic substrate, or a flexible plastic film (for example, a polyimide film, a PEN or PET film, etc.) is pasted on the glass substrate to form the plastic substrate. Then, electronic devices (for example, thin film transistors, circuits, OLEDs, etc.) are formed on the plastic substrate through the same process as that in manufacturing rigid display panels. Finally, the plastic substrate with the electronic devices formed thereon is separated from the glass substrate.
Specifically, the plastic substrate may be separated from the glass substrate by using a laser lift-off method. The principle of the laser lift-off method is as follows: the glass substrate is irradiated with a laser beam, so that certain heat may be generated between the glass substrate and the plastic substrate, so that the bonding force at an interface of the plastic substrate and the glass substrate is reduced, thus realizing separation; then, the plastic substrate and display devices are taken off by simple cutting and mechanical lift-off methods.
As the size of the glass substrate is large, usually, a plurality of flexible display panels may be fabricated on one glass substrate. Therefore, when lifting off the plastic substrate on the glass substrate, it is desirable to separate regions with the flexible display panels, but regions without the flexible display panels (including a region between two adjacent flexible display panels and a region between an edge of the glass substrate and an edge of the outermost flexible display panel) may not be treated. In the process of laser scanning by a laser lift-off method, a laser emitter is turned off when reaching the region without the flexible display panel, while the laser emitter is turned on when reaching the region with the flexible display panel. However, as it is difficult to control the energy of lasers emitted by the laser emitter to be desired energy at the moment when the laser emitter is turned on (usually, the energy of lasers at that moment is far higher than the desired energy), the heat at the interface of the plastic substrate and the glass substrate, on the edges of the flexible display panels, increases sharply. As a result, the plastic substrate is likely to be burned, blackened, deformed or even damaged, which further causes edge portions of the flexible devices to be damaged.
Therefore, how to prevent damage to a plastic substrate of a flexible display panel during laser lift-off and thus to avoid damage to edge portions of a flexible device becomes a technical problem to be urgently solved in the art.